Recently, in view of environmental problems, there is a demand for a small and light secondary battery that is capable of quick charge and large current discharge, in response to a request for a power source that is to be mounted on an automobile or a request for a large tool with DC (with a direct-current power source). As a battery satisfying this demand, there is a nonaqueous electrolyte secondary battery such as a lithium secondary battery in which a negative electrode active material contains metallic lithium, a lithium alloy, or a material capable of intercalating and deintercalating lithium ions (e.g., carbon material) (see Patent Document 1, for example). Such a nonaqueous electrolyte secondary battery contains a nonaqueous electrolyte, and the nonaqueous electrolyte contains, for example, an aprotic organic solvent and a lithium salt dissolved in the organic solvent.
The nonaqueous electrolyte secondary battery can be produced, for example, in the following manner.
A laminate including a sheet-like positive electrode, a sheet-like negative electrode including the negative electrode active material, and a separator disposed between the positive electrode and the negative electrode is wound to form an electrode group. The positive electrode and the negative electrode can include, for example, a current collector and an active material layer disposed thereon. The separator has functions of holding a nonaqueous electrolyte, and preventing a short circuit between the positive electrode and the negative electrode.
Next, the electrode group is accommodated in a battery case made of stainless steel, nickel-plated iron, or aluminum, and a nonaqueous electrolyte is injected into the battery case. Lastly, the opening of the battery case is sealed with a sealing plate, and, thus, a nonaqueous electrolyte secondary battery can be obtained.
Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 5-182693